Out of This World

HWS professor and alumnus partner to
advance science

by Melissa Sue Sorrells Galley '05

The greatest projects in experimental
physics depend on multidisciplinary
collaboration: scientists and
engineers working together to solve
complex problems and move the knowledge
of our universe forward.

As a member of the Laser
Interferometer Gravitational Wave
Observatory (LIGO) Scientific Collaboration,
Associate Professor of Physics Steven
Penn is part of a team of more than 500
scientists, working together to detect and
measure cosmic gravitational waves–ripples
in the fabric of space and time created by
powerful events in the universe.

As president and co-founder of MLD
Technologies, Len Mott '66 works with a team of 25 engineers and technicians to conceive, design and produce
high-performance optical coatings and other optical components used in medical and aerospace instruments.

Together, Penn and Mott, although seemingly involved in unrelated areas of science and technology, have
forged a partnership that is small in scale but galactic in its impact.

"One day about five years ago, I was working at my desk on the Saturday afternoon of Reunion while
everyone else was having fun on the Quad, and there was a knock at my door," says Penn.
On the other end of that knock was Mott, who was visiting campus for his 40th Reunion. "I introduced
myself as the 'M' in MLD Technologies," says Mott.

As it turns out, Mott and Penn have been working together for years, although they'd never met. "My
company makes some of the mirror coatings used in Steve's experiments. But, until recently, I didn't know he
was an HWS professor, and he had no idea I was a Hobart graduate."

Funded by the National Science
Foundation, LIGO is one of the
largest and most ambitious science
experiments in history. When
completed, scientists hope the
Observatory will be able to accurately
measure space-time oscillations
thousands of times smaller than a
proton. Those measurements will
provide invaluable data about black
holes, neutron stars and the birth of
our universe. It will provide a window
on some of the most energetic
events in our universe that cannot be
seen any other way.

As with any project of this size,
there are a number of challenges to
overcome. Penn and his colleagues
are particularly focused on the
limitations of the thin-film coatings
used on LIGO's optical mirrors.
"Currently, our ability to 'see' black
holes and neutron stars is limited
by the optical coatings used on our
mirrors," explains Penn.

Mott's company specializes in
depositing super-thin multi-layers
on optical mirrors using a process
called Ion Beam Sputtering. These
thin-film coatings control reflection
and transmission of light, as
required by the design of the LIGO
instruments.

In order to maximize the
sensitivity of the Observatory,
LIGO requires optical components
with very low absorption and
very low mechanical loss, which
will minimize thermal noise.
"Thermal energy causes the mirror
coatings to vibrate but it makes
it appear that the whole mirror is
vibrating," explains Penn. "We 'see'
gravitational waves by sensing the
location of the mirrors. The thermal
motion in the coating creates a
noise. This motion is tiny, but it is
enormous compared to the ripples
of space-time we try to observe."

"At the moment, we know
we can create low absorption
coatings," explains Mott, whose
company develops prototype
mirrors that have been tested at
HWS and in other labs across the
country. "Our current focus is on
reducing the mechanical loss,
which allows Steve and his team to
evaluate the thermal noise."
Since their initial meeting,
Mott and Penn have stayed in
contact, and Mott even returned
to campus to talk with current
physics majors at Penn's
invitation. "Our majors loved Len's
talk," recalls Penn. "It was like
looking into the future at an image
of what they could achieve."

Both men are confident that
their partnership will bear fruit
and move our knowledge of the
universe forward. "I've worked on
several cutting-edge projects over
the past 40 years," says Mott.
"But this is a really challenging
and exciting one."